Resilient hitch



Nov. 21, 1967 A. 1. LOMMEN ETAL 3,353,843

RESILIENT HITCH Filed March 17, 1966 H /8 FIG. .Z 0 3 33 @/37 Q4 INVENTORS. ALAN J. LON/MEN MER/'SQL M.HAAKEN$O/\/ AT TORNEYS United States Patent 3,353,843 RESILIENT HITCH Alan J. Lommen and Merrel M. Haakenson, both of Dickey, N. Dak. 58431 Filed Mar. 17, 1966, Ser. No. 535,204 9 Claims. (Cl. 280-486) Our invention relates generally to hitches and more specifically to hitches which are adapted to absorb the force of tension or compression between two relatively moving objects. Still more specifically our invention relates to an extensible retractable hitch which uses a length of rope, formed from synthetic fibres such as nylon, as a resilient member for absorbing such forces of tension or compression.

It is a primary object of our invention to provide a telescoping hitch, utilizing a nylon rope which has a high degree of tensile strength, `for absorbing shocks between a pair of relatively moving objects.

It is another object of our invention to provide a device of the class above described which will absorb such shocks with but a nominal amount of telescoping movel ment of the hitch ports.

A further object of our invention is the provision of 'a device of the class above described Which has a slow return action to minimize damage to either of the moving objects between which it is attached.

A still further object of our invention is the provision of a device of the class above `described in which the resilient member thereof may -be prestressed whereby to require a greater amount of stress before same is stretched. v

It is still another object of our invention to provide a device of the class above described which is relatively light in weight, simple and inexpensive to manufacture and rugged and durable in use. r

These and other highly important objects will becom apparent to those skilled in the art upon consideration of the following detailed specification, attached drawings, and appended claims.

With further reference to the drawings wherein like reference numerals indicate like parts throughout the several views:

FIG. 1 is a plan view of the instant invention in an operative position to absorb tensional shock between a pair of relatively moving objects;

FIG. 2 is a view in side elevation of the structure of FIG. l portions thereof being broken away and shown in section;

FIG. 3 is a view in axial section as seen from the line 3--3 of FIG. l;

FIG. 4 is a view in transverse section as seen from the line 4--4 of FIG. 2; and

FIG. 5 is a View partly in elevation and partly in axial section of a modified hitch adapted to absorb the force of compression between a pair of relatively movin-g objects.

With more particular reference to the drawings, and initially to FIGS. 1 4, there is shown a pair of relatively moving objects in the nature of a prime mover such as a tractor and a trailing implement 11, only a portion of each of which is shown. In cases where the trailing implement 11, such as a plow, cornes into engagement with a generally immovable object, in the nature of a rock or the like not shown, it is highly desirable to provide some means to absorb the tensional shock between the tractor 10 and such an implement 11 to minimize the possibility of damage to either thereof. To this end we provide an extensible-retractable, shock absorber or hitch indicated in its entirety by the numeral 12. Shock absorber or hitch 12 is comprised of a pair of tubular members 13, 14, the former of which has an inner end 15 whiru is telescop- 3,353,843 Patented Nov. 21, T967 ically received within the inner end 16 of member 14. Each of the members 13, 14 also include the outwardly flared outer ends 17, 18 respectively. An annular stop collar 19 is slidably received over the tubular member 13 and is anchored thereto, at a selected position along the axis thereof, by means of a set screw 20I to limit axial telescoping movement of the member 13 into the member 14. The reason for the adjustability of the collar 19` will be described in more detail later in the specification.

For the purpose of limiting axially outward movements of the members 13, 14 and thereby resiliently absorb the tensional forces between the tractor 10 and plow 11, there is provided a rope-like tie element 21. In view of the high degree of tensional forces that may be present between the tractor 10 and plow 11, particularly if the plow 11 should come into engagement with an object such as a rock, not shown, tie element 21 is preferably formed from a synthetic fibrous material such as nylon twist rope, that has a high degree of tensile strength. Although nylon is more commonly in use at the present time, other suitable synthetic fabrics having the desirable characteristics of nylon are being developed rapidly. Therefore, we do not wish to be limited to the use of a nylon rope tie element 21 but only `to that which comes within the scope of the appended claims. Compared to manila rope, nylon has a tensile strength of one and one half to two times and a working elasticity of about three times. Also, nylon fibres have a substantially greater resistance to flexing and surface abrasion thus providing a highly desirable synthetic material for use in the tie element 21.

As shown, particularly in FIG. 3 the nylon tie element 21 extends axially within the tubular members 13, 14 and has an opposite end anchored one each to a flared outer end portion 17, 18 of tubular members 13, 14 respectively. The opposite ends of the tie element 21 are anchored by means of a plurality of segmental Wedge elements 22 three of which are telescopically received within each of the ared outer end portions 17, 18. Each three Wedge elernents 22 collectively define a central passage 23 therethrough for clamping reception of an adjacent end of the tie element 21.

A preferred sequence of operation for mounting the tie element 21 within the tubular members 13, 14 is to first slide the collar 19 over the tubular member 13. Thereafter the inner end 15 of member 13 is telescopically received through the inner end 16 of member 14 so as to be fully received therein. Tie element 21 is then passed axially through the members 13, 14 and wedge elements 22 are forced into their respective flared outer ends 17, 18 with the adjacent ends of the tie element 21 received within the central passage 23. While more or less pressure might be required it was found during experiments that approximately 50,000 pounds of pressure were required to seat the wedge elements 22 in their respective flared outer ends 17, 18 to properly clamp the ends of the tie element 21. Therefore, a jack or press must be used to position the wedge elements 22 in their respective outer end portions 17, 18. As the wedge elements 22 pass axially into the flared outer ends 17, 18 same cooperate with their adjacent outer ends 17, 18 to securely clamp the end of the tie element 21 associated therewith. With the opposite ends of the tie ele-ment 21 securely clamped, tubular elements 13, 14 and collar 19 may be moved -to the position shown in FIGS. 1-3 and there locked against further axial movement by means of the set screw 20. In this position it Will be seen that the tie element 21 is held taut and disposed in a position within the tubular members 13, 14 wherein there is no chance for frictional engagement with the side walls thereof. Thus, no chafling or rubbing engagement of the tie element 21 with the side walls of the members 13,

14 occurs during telescoping movements to cause undue wear and subsequent rupture of the tie element 21.

The coefficient of sliding friction between the several strands of rope formed from nylon bres is relatively low. Therefore, in order to prevent the centrally located strands or fibres of the tie element 21 from slipping relative to the outer strands, the wedge elements 22 in each of the flared outer ends 17, 18 have inner end portions 24 which project radially inwardly to dene a diametrically reduced portion of the passage 23. With this arrangement a maximum of clamping force is applied to the tie element 21 at the point of engagement of the portions 24 therewith. To further assure that slipping of the center bres relative to the outer fibres of nylon tie element 21 does not occur the strands adjacent the extreme outer ends of the tie element 21 are heated to substantially the melting point to form a disk-shaped wafer 25. Wafer 25 ties the ends of the strands or fibres of the tie element 21 together and seals the central passage 23 formed by the wedge elements 22 in each of the flared outer end portions 17, 18. Additionally the surfaces of the wedge elements 22 which dene the passage 23 are knurled or roughened as at 26 axially outwardly of the portions 24 to more securely grasp or clamp the outer-strands or fibres of the element 21.

Welded or otherwise secured to each of the flared outer ends 17, 18 are diametrically opposed axially extended rods 27, 28. Rods 27, 28 are each provided at their outer ends with eye portions 29, 30. Cooperating eye portions 29 as well as cooperating eye portions 30 are coaxially disposed on axes which extend in a direction normal to the longitudinal axis of the members 13, 14. Eye portions 29, as illustrated, may be attached to the draw bar of a tractor 10 by means of a pin 31 while eye portions 30 may likewise be attached to the frame of an implement 11 being pulled by the tractor 10 by means of a pin 32.

A serious drawback to the use of nylon rope is the sensitivity of the fibres thereof to heat generated under constant flexing during the application of tensional forces thereto. To alleviate this problem and prevent deterioration of the nylon tie element 21 same is impregnated with a suitable lubricant, not shown, prior to assembly of the shock absorber or hitch 12. Also, the tubular members 13, 14 are provided with zerk fittings 33 which allows introduction of additional lubricant into the tubular members 13, 14 between the wedge elements 22. This arrangement assures a constant supply of lubricant to the 4tie element 21 during use with the result that a minimum of heat is generated during operation.

In many instances it is necessary to back the implement 11 up, an example being in the use of a trip beam plow, where it is often necessary to back the plow up to reset a tripped beam thereof. To accomplish this operation in a manner wherein the implement or plow 11 does not easily jackknife with respect to the tractor 10, -we provide means in the nature of an elongated brace 34 for locking pivotal movement of the shock absorber or hitch 12 about pin 32. One end of the brace 34 is connected to the implement 11, laterally of the pin 32 as at 35, and the other end thereof is connected as at 36 to an adjustable clamp 37 which is carried by the tubular member 14. It will be appreciated that the hitch 12 will work equally well should it be turned end for end and is shown in its present position only for purposes of illustration. Also it will be appreciated that the hitch 12 may be utilized in other ways where there are tensional forces between a pair of relatively moving objects. An example of such use would be the substitute of the two lower pulling links of a three point hitch, not shown, with a pair of our shock absorbers or hitches 12.

In FIG. a modified embodiment is shown wherein means is provided for converting the force of compression between two relatively moving objects, not shown, to tensional force as applied to the shock absorbers or hitch 12. Shock absorber or hitch 12 shown in FIG. 5 is identical to that ,shown in FIGS. 1-4 with the brace 34and clamp 37 removed therefrom and therefore like numeralsy are used during further specificy reference thereto. As shown, the means for converting such force of compression to such force of tension as applied to the hitch 12 comprises a first and second tubular element 38, 39. Each of the elements 38, 39 define an axial passage 40, 41, respectively, and an outer end portion 42, 43, respectively. One each of the portions 42, 43 is adapted to be connected to one of a pair of relatively moving objects, not shown, by clamps or pins also not shown. An inner end portion 44 of element 38 is telescopically received through the inner end portion 45 of the element 39 and is disposed within the axial passage 41 defined by the element 39. Positioned within the passage 40 with the eye portions 30 adjacent the inner end 44 of element 3.8 is the shock absorber or hitch 12. A pin 46 extends through the eye portions 30 and has opposite ends thereof positioned one each in one of a pair of diametrically opposed apertures 47 formed in the inner end portion 44 of element 38 to thus mount one end of the shock absorber or hitch 12 to the element 38. The other end of shock absorber or hitch 12 is secured to the inner end 45 of element 39 by means of a pin 48. Pin 48 extends through the eye portions 29 of tubular member 13 and through a pair of longitudinally extended diametrically opposed slots 49 formed in the element 38 and thence through a pair of diametrically opposed apertures 50 formed in the inner end portion 4S of element 39. An enlarged head 51 together with a nut 52 limits axial movement of the pin 48. Thus, the other end of shock absorber or hitch 12 or the outer end of tubular. member 13 has been fixedly mounted to the inner end portion 45 of element 39, The slots 49 formed in the element 38 permit axial movement of the element 38 with respect to element 39. With the above arrangement it will be seen that any force of compression applied at the outer ends 42, 43 of the elements 38, 39 respectively will be applied to the shock absorber or hitch 12 as tensional force. It will again be pointed out that the shock absorber or hitch 12 together with the .tubular elements 38, 39 will operate equally well if turned end for end during use.

It will be here noted that in both the above described applications of the shock absorber or hitch 12, the collar |19 may be adjusted axially of the tubular member 13 to pre-stress the tie element 21. Also, should the tie element 21 become slack under repeated use same may be brought back to a taut condition by such adjustment of the collar 19. It will also be noted that nylon rope has a relatively slow rate of recovery or spring back as opposed to that of a steel spring. As such, less strain from impact or tension is imparted to the hitch 12 and/ or the tractor 10 and implement 11 with the result of less damage to same.

My invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the above objects, and while I have shown and described a preferred embodiment, I wish it to be specifically understood that the same is capable of modification without departure from the spirit and scope of the appended claims.

What is claimed is: 1. A shock absorber adapted to be interposed between a pair of relatively movable objects comprising:

(a) a pair of tubular telescoping members each having an axially outwardly flared outer end portion, (b) adjustable means limiting inward telescoping movements of one of said members into the other of said members,

(c) a rope-like tie element Vformed from synthetic fibrous material extending axially within said tubular members,

(d) anchoring means associated with said ared outer yend portions of said tubular members for anchoring an ,Opposite end of said tie element to one each thereof, and

(e) means for detachably pivotally securing said flared outer vend portions of said tubular members one each to one of a pair of relatively moving objects whereby to absorb tensional forces therebetween.

2. The structure of claim 1 in which said tie element is impregnated with a lubricant.

3. The structure of claim 2 in further combination with a fitting for introduction of lubricant into said passage of said tubular member between said anchoring means whereby said tie element is impregnated with lubricant.

4. The structure of claim 1 in further combination with means interposed between one of said tubular members and an object to which it is attached whereby to lock said pivotal connection thereof against pivotal movements relative to said object.

5. The structure of claim 4 in which said segments in each of said ared outer end portions include inner ends which cooperate to define a diametrically reduced portion of said passage.

6. The structure of claim 1 in which the means associated with said flared outer end portions for anchoring the opposite ends of sai-d tie element includes a plurality of segmental Wedge elements teleseopically received in each of said ared outer end' portions, said wedge elements received in each of said flared outer end portions collectively defining a central passage therethrough -for reception ofthe adjacent end of said tie element.

7. The structure of claim 1 in which the means for detachably pivotally securing said flared outer ends of said tubular members includes an eye portion associated with each thereof having axes which extend normal to the axes of said tubular members .and in further combination with means secured to said eye portions for absorbing the forces of compression between a pair of relatively moving objects.

8. The structure of claim 7 in which the last mentioned means comprises:

(a) a first and second tubular element each defining an axial passage and each having an outer end portion adapted to be connected to one of a pair of relatively moving objects and an inner end portion with the inner end portion of the first tubular element telescopically received within the inner end portion of the second tubular element,

(b) said pair of tubular members being disposed axially within said passage of said first tubular element,

(c) means securing one of said eye portions to said inner end portion of said first tubular'element, and

(d) means securing the other of said eye portions to said inner end portion of said second tubular element whereby to permit limited relative telescoping movement between said first and second element.

9. The structure of claim 8 in which said first tubular element defines `diametrically opposed, longitudinally extended slots formed in an intermediate portion thereof and in which said last mentioned means comprises an anchoring pin extending through said other eye portion, diametrically opposed slots, and inner end portion of said second tubular element.

References Cited UNITED STATES PATENTS 2,751,218 6/1956 Pass 267-69 2,797,082 6/ 1957 Weigel 267--73 2,888,257 5/1959 Taylor 267-1 3,068,944 12/ 1962 Renshaw 280-486 X FOREIGN PATENTS 449,157 12/1912 France.

LEO FRIAGLIA, Primary Examiner. 

1. A SHOCK ABSORBER ADAPTED TO BE INTERPOSED BETWEEN A PAIR OF RELATIVELY MOVABLE OBJECTS COMPRISING: (A) A PAIR OF TUBULAR TELESCOPING MEMBERS EACH HAVING AN AXIALLY OUTWARDLY FLARED OUTER END PORTION, (B) ADJUSTABLE MEANS LIMITING INWARD TELESCOPING MOVEMENTS OF ONE OF SAID MEMBERS INTO THE OTHER OF SAID MEMBERS, (C) A ROPE-LIKE TIE ELEMENT FORMED FROM SYNTHETIC FIBROUS MATERIAL EXTENDING AXIALLY WITHIN SAID TUBULAR MEMBERS, (D) ANCHORING MEANS ASSOCIATED WITH SAID FLARED OUTER END PORTIONS OF SAID TUBULAR MEMBERS FOR ANCHORING AN OPPOSITE END OF SAID TIE ELEMENT TO ONE EACH THEREOF, AND (E) MEANS FOR DETACHABLY PIVOTALLY SECURING SAID FLARED OUTER END PORTIONS OF SAID TUBULAR MEMBERS ONE EACH TO ONE OF A PAIR OF RELATIVELY MOVING OBJECTS WHEREBY TO ABSORB TENSIONAL FORCES THEREBETWEEN. 